6850 Crossfire still doesn't work

[tjcoops]

I've got an Arctic Freezer 7 with Arctic MX4 as my thermal paste, I think the CPU temps are accurate because when I was running some ABSOLUTELY TERRIBLE thermal paste the CPU got to about 64c under load.

 

[amirp]

For F1-2011 you gotta download this: http://downloads.guru3d.com/AMD-Catalyst-Application-Profile---11.11-CAP2-download-2782.html
the newest application profiles have f1-2011

and CPUTIN is nothing relevant im pretty sure, it doesnt correlate with your core temp.
for example right now my 2500k at idle is ~27-29 but CPUtin says 60 with no change. I dont even know what CPUtin is lol

Your cpu temp is definitely higher than 40 at those overclocks and with that cooler


So we've solved the problem then, there was no way your old PSU with only 30A was going to power up your entire system!
Get a new power supply 650 - 750 watts of a GOOD brand. Get one with enough PCI-E connectors so you dont have to use those molex converters too.

 

[MasterMace]

CPU temp looks off unless you have exotic cooling. 40c under load is way to small.

This is not off, I have a Athlon II X4 620 OCed from 2.6ghz to 3.4ghz and under torture it gets to 42c.

--

Your PSU is no bueno amigo. Your PSU review

It drops voltage hard on the 12v. It's not that a 650W is not enough power, it's that the rails can't move the power. If you have to upgrade your PSU, you might as well get a 750W instead of a 650W though. The Corsair TX750W is a very good brand, and very well reviewed PSU.


That being said, your PSU is not your only problemo, seeing as you tested it on a KW PSU. Try switching which slots the cards are in. If card 1 was in slot a, and card 2 in slot b, stick card 1 in slot b, and card 2 in slot a. Test it. This will show you how much of an impact your slots have on the card's usage.


*edit*

Forgot to post this link. The CM PSU you have failed mid-review for these guys:

 

[amirp]

MasterMace ... read the entire thread, we found out his PSU WAS the problem and those tests you've asked him to do he has already done. He said F1-2011 is the only game which hasnt improved since switching to the better PSU. Also 650watt IS enough power for him, its just that this particular power supply was supplying only 30A x 12V = 360 watts on 12v rail, and as you and I have said it's not very good.

Also the 40 degrees is CPUTIN, what is that? I dont think that corresponds to Core temp, also his ambient temp, cpu, cpu cooler, and overclock are all different from yours, so what your cpu reaches is irrelevant.

 

[jjb8675309]

get a new psu and mobo--- also your original cpu should have been fine imo...

your psu is honestly crap and is likely not supplying the cards like they should be (even though the 6850s do not require much)

there will be inherent microstutter but I would not expect negative scaling, overall they are a terrible solution in crossfire imo

if you really want to properly run crossfire you should at least get an 8x8 board although a 16x4x board should necessarily kill the performance but I would go with a better board in the future perhaps a 99XX

 

[tjcoops]

get a new psu and mobo--- also your original cpu should have been fine imo...

your psu is honestly crap and is likely not supplying the cards like they should be (even though the 6850s do not require much)

there will be inherent microstutter but I would not expect negative scaling, overall they are a terrible solution in crossfire imo

if you really want to properly run crossfire you should at least get an 8x8 board although a 16x4x board should necessarily kill the performance but I would go with a better board in the future perhaps a 99XX

Yeah, despite my improved performance I know if my frame rates drop too much I might start suffering from microstutter. Thinking of the Asus Sabertooth 990FX as its dual x16 and a bit future proof (maybe future resistant )

I have effectively stolen my Dad's KW power supply as I know he won't go through the effort of removing it

Anyone think it would be a good idea to make a sticky reitterating the importance of the psu in crossfire and sli setups. Although I was aware of psu manufacturers lying about their power supplies before this thread, I would have never guessed that a power supply rated at 650w from a half decent brand wouldn't power a system requiring barely 500 watts.

 

[amirp]

no dont waste your money on a 16x 16x board, you definitely dont need that for 6850s!!! And you will still have microstutter. Not to mention it cant really be future proof unless AMD actually releases good processors for it.
Best advice other than leaving things how they are, sell 6850s and any money you were going to use on the motherboard/psu on a stronger single card (if you aren't happy with what you have now).

And did you download the file from the link I gave above for F1-2011? that should fix it

 

[lolzxdrofl]

ok i want you to go to CCC and change the setting to performance instead of quality bcuz even though it says "quality" it just uses more of ur processes when u change them the fps will look like 80-100 bcuz i have the same problem when u change the 2 it fixes the fps, and mine was 650W had the same problem, and if u cant find the performance/quality, i think its under displays or gaming, im currently not home so try ur best to find it.
the performance makes it run smoother.
also, 6850 crossfire can be quite bad in x16/x4, the "fps" could be from the motherboard, im not totally sure but if u want a really good mobo get the Gigabyte 990fxa-ud3 dont waste 40$ extra for the saber tooth because there both x16/x16, and the gigabyte has Dolby, if you get the saber tooth it means you are actually considering 3 way crossfire which isnt possible with 6850 crossfire so just get the 990fxa-ud3 for ur 2 cards but thats only if u want x16/x16, it has same o.c abilities EasyTune6 allows u to re-unlock you're processor

 

[amirp]

OP.... any updates?

 

[tjcoops]

I don't usually 'revive' dead posts but I thought it was necessary here as there was a lot of good discussion and I thought I'd share my findings.

I tried EVERYTHING! and I appreciate everyone's help last year, here are my findings:

I started with a x16/x4 board, a 650w PSU with and AMD Athlon X4;
Results were terrible with 6850 crossfire.

I upgraded to a 1010w PSU as my poor quality 650w was not providing enough power
Results were better, not good.

I upgraded at Christmas 2011 to a x16/x16 board with an Phenom X4;
Results were sporadic at best, sometimes an increase, mostly a decrease in performance.

In Feb/March I upgraded to Intel Mobo x16/x8 /CPU, a 2500K
Results were much better! Usually games saw a healthy increase in frame rate, but stutter was still visible

Now I have upgraded to a single Sapphire HD7950 and OCed to 1200/1400
Results are brilliant, silky smooth gameplay!

 

[amirp]

thanks!